Usually, a seat slide apparatus for a vehicle includes an upper rail supporting a seat at an upper portion thereof and a lower rail supporting the upper rail in a state where the upper rail and the lower rail are movable relative to each other. In many cases, the upper rail is made from plate material which is bent or folded.
For example, according to a seat slide apparatus described in JP2004-90765A (which will be hereinafter referred to as Patent reference 1), an upper rail includes a pair of vertical wall portions facing each other and a bent portion connecting upper portions of the vertical wall portions to each other. A threaded portion used for fastening a seat is provided at each lengthwise-direction-end portion of the upper rail.
Further, JP2003-252087A (which will be hereinafter referred to as Patent reference 2) discloses a configuration where a reinforcement member formed in a plate shape is provided between vertical wall portions which constitute an upper rail. Thus, a support rigidity of the upper rail may be enhanced.
However, for example, at a vehicle collision, an extremely large load which is caused by an external force acting on the seat is applied to the upper rail. In order to avoid a deformation of the upper rail which is caused by such external force, the support rigidity of the upper rail is desired to be even more enhanced. Therefore, room for improvement remains in this regard.
A need thus exists for a seat slide apparatus for a vehicle, which is not susceptible to the drawback mentioned above.